"The British are Coming, the British are coming!" Let's break it down into Palinese:
(1) "The British..." was shorthand for "Hey all you Britsh people living in the colonies..."
(2) "are" as defined in the Palin to English dictionary does not describe an actual state of being, but rather describes the state of being which best serves the speaker's agenda. For example, "liberals are nazis". This can be a challenge for interpreters because the predicate noun is not an actual representation of the state of the subject. While not technically accurate, as a convenience, the word "are" is often translated as "are not".
(3) "coming". Palinese has a very unique attribute among human languages, which some scholars believe actually remove it from the realm of a spoken "language" and more in the realm of a series of signals, much like nautical semaphores. Every word is falls into two categories sometimes described "good" and bad". However, since Palinests do not understand these concepts in traditional terms, many scholars prefer to categorize these terms as either "alarming" or "smug". "Coming" is always in the "alarming" category. For example "death panels are coming to take away our health care." "Admired" exemplifies the "smug" category. For example, "I admire Hillary Clinton".
(4) ellipses. Every sentence uttered in Palinese, must contain either the phrase, "take away our freedom" or "take away our guns." In Palinese, "guns" and "freedom" are synonymous and both represent what speaker's of English refer to as "the law of the jungle". Whereas most people would agree that the "freedom" to shoot our neighbors in the head is actually something the government should be involved in preventing, in Palinese, it falls within the "smug" category of acceptable political expression. In the event, a speaker of Palinese neglects to mention "take away our guns" or "take away our freedom" they may be considered as ellipses and should be supplied by the interpreter.
Now, understanding just these few points about Palinese, you can clearly see why Ms. Palin is convinced that she has correctly reflected the meaning and purpose of the phrase, "The British are coming." Palin incorrectly assumes that Paul Revere was speaking in Palinese and not in English. In Palinese, what Paul Revere actually declared during his midnight ride was, "Hey all you British people, it serves my agenda to assert express alarm that you are coming to take our guns."